1. Field of the Invention
The present invention relates to the elimination of hazardous radioactivity and, more especially, to the elimination of that radioactivity attributed to radium, from aqueous nitrate/radium solutions by liquid/liquid extraction.
2. Description of the Prior Art
Numerous hydrometallurgical processes result in the creation of radioactive effluents, which must be treated such as to diminish their radioactivity below a certain threshold imposed by law for their discharge into waterways or the seas.
Particularly exemplary of such processes is leaching, for the treatment of uranium containing minerals or rare earth minerals, such as monazite or apatite. Over the course of these processes, uranium or rare earth compounds are recovered, together with effluents notably containing radium 226 and 228, especially in a nitrate medium. The most severe regulations impose on these effluents a maximum radium content of 30 p Ci/l for radium 228 and 10 p Ci/l for radium 226.
A known treatment for the recovery of these radioactive elements consists of the precipitation of a compound that it is only very slightly soluble in water, such as barium sulfate. Thus, a solid containing radioactive species is obtained, which may be transported to a center for the treatment of radioactive waste.
However, this precipitation method is expensive, as the reagent cannot be recycled. Furthermore, in certain cases it may be too inefficient, in particular in the case of effluents comprising a nitrate medium, as nitrates are complexing agents for radium.